Combine potatoes, carrots, onion, water, bouillon cubes, pepper and salt in a large saucepan.

Cover and cook for about 20 min. or until potatoes are tender, but not mushy.

Add 1 c. milk, heat.

Combine sour cream, flour, chives and remaining 1 c. milk. Stir mixture into soup gradually.

Cook over low heat, stirring constantly until thickened.

Garnish with cheese if desired.